Conventional drivelines for automotive vehicles include a driveshaft that is connected to a driven pinion. A drive pinion includes a pinion shaft that is journaled by a pair of axially spaced bearings. These two bearings are separated by a spacer. During vehicle operation driveline vibrations, gear separation forces, or unbalancing forces can occur within the drive pinion which cause deflection in the pinion assembly components. Therefore, it is desirable to preload pinion assembly components in a driveline differential in order to accomplish target NVH functionality and durability.
Different methods exist within the art for preloading pinion bearing assemblies used in driveline differentials. Bearing pre-load is traditionally set by monitoring a maximum rotational drag torque on the bearing assembly while tightening the distance between bearings. With this method the expected drag torque levels for a 5-9 kN pre-load may be in the 1.7-2.3 Nm torque range. However, using drag torque to decipher preloading has its detriments. For example, drag torque resulting from loading varies depending on the level of rust inhibitor used, lubrication provided, whether or not a seal interface drag is used, and ambient temperature. Additionally, angular contact ball bearings (or “ACBBs”), with reduced drag for fuel efficiency have expected drag torque levels in the range of 0.21-0.23 Nm. This is a significantly reduced level of drag torque as compared to 1.7-2.3 Nm. Accordingly, with ACBBs it is much more difficult to measure the reduced drag or set preloading.
U.S. Pat. No. 7,251,892 titled “Bearing Assembly Spacer Adjustable System and Method for Adjusting a Spacer” teaches the use of a spacer adjustment system having a preloading regulator that controls preloading according to the deformation desired, using electrical contacts between a first and second portion of the spacer to measure a travelled distance. This system, however, relates to spacer adjustment instead of preloading for the entire pinion assembly. In an assembly, the displacement for target preload can vary depending upon the elastic modulus of each component.
Therefore, it is desirable to have pinion assembly preloading systems (and methods for the same) that preload the entire assembly and do not require the use of a measured drag torque.